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Chapter 4 of 22
Revision Notes

Atmosphere

Kerala Board · Class 9 · Social Science

Quick revision notes for Atmosphere — Kerala Board Class 9 Social Science. Key concepts, formulas, and definitions for last-minute revision.

44 questions20 flashcards5 concepts

Key Topics to Revise

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1. Composition and Structure of Atmosphere

  • Atmosphere is a sea of gases about 1000 km thick surrounding Earth
  • Major gases: Nitrogen (78%), Oxygen (21%), others including CO2, water vapour, argon
  • Water vapour accounts for 0.4% but concentrated within 6 km of Earth's surface
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2. Air Pressure and Pressure Belts

  • Air pressure is the force exerted by air molecules on any surface
  • Pressure decreases with altitude and increases with cooling
  • Hot air rises creating low pressure, cool air sinks creating high pressure
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3. Planetary, Seasonal and Local Winds

  • Planetary Winds: Trade winds (easterlies in tropics), Westerlies (temperate zones), Polar easterlies
  • Trade winds: NE in Northern hemisphere, SE in Southern hemisphere
  • Westerlies: SW in Northern hemisphere, NW in Southern hemisphere
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4. Weather and Climate

  • Weather: Short-term atmospheric conditions (daily changes)
  • Climate: Long-term average weather patterns (decades of data)
  • Elements of weather and climate: Temperature, pressure, wind, humidity, precipitation

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Full Notes

Key Concepts

The atmosphere extends up to 1000Air pressure decreases with altitudeGlobal pressure belts form dueHumidity is water vapor in airThree main types

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Frequently Asked Questions

What are the important topics in Atmosphere for Kerala Board Class 9 Social Science?

Atmosphere covers several key topics that are frequently asked in Kerala Board Class 9 board exams. Focus on the core concepts listed on this page and practise related questions to build confidence.

Start by understanding all key concepts. Practise previous year questions from this chapter. Revise formulas and definitions regularly. Use flashcards for quick revision before the exam.

Sources & Official References

Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.